Commitment is a general phenomenon observed in all differentiating cells. It describes the fact that the differentiating cells reach a state after which they continue the differentiation process even when they are returned to an environment in which they would ordinarily continue to grow and not start to differentiate. The Laboratory is investigating the timing of commitment of sporulation with respect to cell transfer from different media to various new media. It is also determining the cause of the commitment process with respect to individual carbon sources. In addition, mutants deficient in branched-chain acid synthesis are used to determine the effect of the ratio of branched-chain to straight-chain fatty acids on cell septation as it is observed during growth and sporulation.